The invention relates to semiconductor manufacturing processes, and more particularly, to methods for determining tool assignment preference for semiconductor manufacturing systems, enabling ontime delivery and maximum move for manufacturing products.
In semiconductor manufacturing for production implementation, some (semiconductor) fabrication factories request ontime delivery, some (memory) fabrication factories request the maximum tool utility rate and move, and others mix the above production modes for requesting make-to-order and make-to-stock productions, considering ontime delivery and the maximum move both. The relationship, however, between manufacturing cycle time and tool utilization represents a trade-off. Additionally, the assignment to bottleneck tools seriously affects the manufacturing cycle time and tool utilization, considering tool variation, product specification limitations, or move qualities, such that each tool in the same group may produce different manufactures, resulting in tool assignment troubles if a type of manufacture is required.
FIG. 1 is a schematic diagram showing the relationship between tool variations and processes. In an embodiment of the present invention, tools 1˜6 belong to the same group and are used for production and manufacturing, and processes 1˜7 are applied to the described tools for production and manufacturing, with the number thereof not intended to limit the present disclosure. Tool 1, for example, can execute processes 2, 3, 4, and 6. Process 3, for example, can be applied to tools 1, 2, and 7. Processes applied to each tool may not be entirely the same, and, when processes must be implemented on a wafer lot and tools executing the processes are assigned using a current assignment method, manufacturing damage may occur and efficiency decrease. Thus, according to some bottleneck tools causing manufacturing limitations, it is obviously important to determine assignment preferences of products and processed tools.
As described above, due to tool variations, restrictions to each tool in the same group to produce a portion of products, and move limitations to each tool, improper assignment of preferences to tools results in move loss and delivery delay. Thus, an improved method for determining tool assignment preference is desirable.